The present invention relates to the field of thermal treatment of coal particularly in solid bed pressure-type gas generators for producing sewer or synthetic gases, wherein slag forming materials are subjected to gasification.
More particularly, the present invention relates to a slag breaker for a pressure-type coal gasifier.
During pressure-type coal gasification with reduced ratio of vapor-oxygen, an increased slag component in ash takes place because of the high temperature in the reactor, which can lead to disturbances in the ask discharge system. There are many proposals to reduce the slag content in the ash discharge system. In accordance with the patent of the German Democratic Republic No. 15,042 a slag breaking device is provided between a rotary grate and a cooling water jacket of a generator in a pressure-type gasifier. The rotary grate is equipped at its periphery with breaking teeth and formed as a coffeemill-like breaking mechanism together with a breaking ring which is stationarily mounted opposite to the cooling water jacket and also provided with breaking teeth. This construction possesses the disadvantage in the fact that the discharge opening between the rotary grate and the generator cooling water jacket is narrowed, which prevents a uniform lowering of the coal filling in the reactor and results in a so-called wall formation, or in other words depositing and clogging of ash over the outer breaking rim to the height of the generator roof. When the breaking is performed in accordance with this approach, the starting moment is very high so that drive damages must be taken into consideration.
The patent of the German Democratic Republic No. C10J/227156 discloses a slag comminuter in which a stationary central column is arranged centrally below the rotary grate in a milling shaft and provided with breaking arms, and the opposite inner wall of the hollow shaft is provided with a cam. This breaking device is very expensive inasmuch as mounting of the central column is problematic.
A Czechoslavakian publication discloses a rotary grate formed as a slag breaker and shaped as a rounder unilateral triangle. Big slag pieces in this construction get in the wide gap between the rotary grate and the water jacket and then displace, because of the grate rotation, to the gap of smaller width and broken therein. Practical experiments have shown that in this solution displacement of the ash discharge takes place.
U.S. Pat. No. 4,073,629 discloses a breaking device which includes a two-roller breaker located under the rotary grate. This construction is provided with a separate drive which is disadvantageous and requires special and repair-expensive sealing.
Generally speaking it is possible to arrange all known breakers below the rotary grate or the closing system in the ash discharge. The disadvantage of this arrangement of the breakers arranged in the ash discharge corresponds to the disadvantages of the above-mentioned two-roller breaker according to U.S. Pat. No. 4,073,629 and thereby such a construction is unacceptable.